Chinese unmanned lunar orbiter returns home
Beijing: China succeeded on Saturday in the world's first mission to the Moon and back for some 40 years, becoming the third nation to do so after the former Soviet Union and the US.
The test lunar orbiter, nicknamed "Xiaofei" on Chinese social networks, landed in Siziwang Banner of China's Inner Mongolia Autonomous Region early Saturday morning, Xinhua reported.
The last documented mission of this kind was taken up by the Soviet Union in the 1970s.
"Xiaofei" means to test technologies that will be used in the Chang'e-5 mission, scheduled for 2017 when an unmanned spacecraft will land on the moon, collect a soil sample and return to Earth.
The landing site was about 500 km away from Beijing.
Launched Friday last week, the orbiter traversed 840,000 km on its eight-day mission that saw it round the far side of the Moon and take some incredible pictures of Earth and Moon together.
The re-entry process began at around 6 a.m. Saturday morning, with the orbiter approaching Earth at a velocity of about 11.2 km per second.
The high speed led to hefty friction between the orbiter and air and high temperatures on the craft's exterior, generating an ion sheath that cut off contact between ground command and the orbiter.
To help it slow down, the craft was designed to "bounce" off the edge of the atmosphere, before re-entering again. The process has been compared to a stone skipping across water, and can shorten the "braking distance" for the orbiter, according to Zhou Jianliang, chief engineer with the Beijing Aerospace Command and Control Centre.
"Really, this is like braking a car," said Zhou, "The faster you drive, the longer the distance you need to bring the car to a complete stop."
The "bounce" was one of the biggest challenges of the mission, because the craft must enter the atmosphere at a very precise angle. An error of 0.2 degrees would have rendered the mission a failure.
Wu Yanhua, vice director of China's State Administration of Science, Technology and Industry for National Defense, said the test mission has gathered a lot of experimental data and laid a solid foundation for future missions.